The present invention relates to a spun yarn manufacturing method. Ring spinning method has been the principal spinning method throughout the history of spinning method since ring spinning method was developed. Recently, innovative spinning methods, such as open-end spinning method, false-twist spinning method and bundling spinning method, have been developed to achieve remarkable increase in spinning speed as compared with ring spinning method.
In a yard produced through ring spinning method, most component fibers are arranged in parallel and are turned generally in one direction to form a structure of a yarn commonly called as a single yarn having actual twists. In spinning a yarn according to ring spinning method, the yarn forms a balloon of a certain size due to the high-speed revolution of the traveler and the component fibers are twisted with the respective opposite ends thereof being caused to project over the surface of the yarn by a centrifugal force of a magnitude corresponding to the revolving rate and the diameter of the balloon, so that fluff is formed over the surface of the yarn and the fluff is increased by the rubbing action of the traveler on the yarn.
A rotor open-end spinning method is a representative open-end spinning method. However, according to the rotor open-end spinning method, since the component fibers are twisted while they are deposited practically in parallel arrangement over the inner circumferential wall of a rotating rotor, that is, the component fibers are twisted while they are scattered over the preceeding component fibers, the core fibers are highly twisted, whereas the outside component fibers are low twisted and are not twisted firmly around the core fibers. Consequently, the rotor open-end spinning method is incapable of producing such a yarn as a ring-twisted yarn in which all the component fibers are twisted integrally in a parallel arrangement. Accordingly, the fibers scattered in the last stage of rotor-twisting become so called bridge fibers or lap fibers which wind merely round the yarn, are not arranged along the direction of the twist of the yarn and twine themselves round the yarn degrading the appearance of the yarn and causing the reduction of the yarn strength and the production of fluff.
False twist spinning methods or bundling spinning methods are disclosed in Unexamined Patent Publication No. 56-79728, Examined Patent Publication No. 52-43256 and Examined Patent Publication No. 52-43257. According to those methods, the main part of a yarn is formed of 80 to 90% of the component fibers in a parallel fiber bundle and a small number of fibers are wound round the main part to bind the parallel fiber bundle so that a yarn strength is provided. The strength of such a yarn, setting a long staple yarn aside, particularly as short staple yarn formed by merely winding staple fibers round a practically zero-twisted parallel fiber bundle is low and since staple fibers are wound round the parallel fiber bundle with the respective opposite ends thereof being unrestrained, fluff is formed over the surface of the yarn.
According to a spinning method disclosed in Examined Patent Publication No. 55-4857, a passive or positive mechanical force, such as a frictional force, produced by vibration or ballooning is applied to a twisted fiber bundle twisted in a false-twisting zone to draw out fibers included in the fiber bundle in parallel to the yarn axis and those drawn-out parallel fibers are caused finally to wind round the fiber bundle in an untwisting zone after the twisting point of a false-twisting machine and thereby a bundled spun yarn is formed.
In either method, fibers arranged parallel in the twisting zone before the twisting point are used for finally binding the yarn, therefore, those bundling fibers are incapable of providing a high binding force.
That is, according to a bundling spinning method, the yarn structure is defined by making the minor part of the component fibers wind round a parallel fiber bundle consisting of the major part of the component fibers, therefore, the yarn comprises two parts, namely, a major fiber group forming the core part of the yarn and a minor fiber group winding round the yarn. Accordingly, such spinning methods have a disadvantage that although a satisfactory yarn strength is provided for the yarn when the yarn consists of relatively long fibers, sufficient yarn strength can not be provided for the yarn when the yarn consists of short fibers.
Accordingly, the present invention has been made to eliminate the disadvantages of abovementioned various spinning methods.